Factors influencing the stability of ranitidine in TPN mixtures

The stability of ranitidine in TPN mixtures has been widely studied with varyingresults. The evidence suggests that ranitidine is unstable and should be added within 24 h of administration, although other reports indicate ranitidine is stable for at least 14 days. The causes of ranitidine degradation in TPN mixtures were therefore studied in mixtures without fat emulsion using a stability-indicating HPLC method. The results indicated that the stability of ranitidine at 5°C depended on the commercial source of amino acid, additives and type of bag used. The principle mechanism of degradation was identified as oxidation. Ranitidine was more stable in EVA bags in the absence of the trace element additive, which appeared to accelerate ranitidine oxidation. Ranitidine was most stable in mixtures compounded in multi-layered bags. The results suggest TPN mixtures with ranitidine in multi-layered bags could be assigned shelf lives of at least 14 days at 5°C, depending on the amino acid infusion used in the regimen.